1. Field of the Invention
Exemplary aspects of the present invention relate to a synchronous rectification switching regulator and a switching method, and more particularly, to a synchronous rectification switching regulator and a switching method for quickly interrupting a reverse current after detection of the reverse current.
2. Description of the Related Art
A related-art switching regulator of synchronous rectification type includes a configuration for detecting and interrupting a reverse current. FIG. 1 illustrates a switching regulator 100 as one example of the related-art switching regulator of synchronous rectification type. The switching regulator 100 is a step-down switching regulator. In the switching regulator 100, when a small load is applied, a reverse current flows from an output terminal 104 to a ground voltage GND via an NMOS (N-channel metal oxide semiconductor) transistor QN1. To prevent generation of the reverse current, a detection circuit 131 quickly detects when a voltage of a junction K, which connects a PMOS (P-channel metal oxide semiconductor) transistor QP1 with the NMOS transistor QN1, undershoots the ground voltage GND and then increases to a level above the ground voltage GND again, at which time the detection circuit 131 quickly turns off the NMOS transistor QN1 to prevent generation of a reverse current and to reduce power consumption.
When the detection circuit 131 detects a reverse current, the detection circuit 131 turns off the NMOS transistor QN1 via an output driver 132. Therefore, a time-lag occurs between a detection of a reverse current and a turning-off of the NMOS transistor QN1. Specifically, the reverse current flows from the output terminal 104 through a coil L for a longer time period, resulting in decreased efficiency.